Clutch and brake mechanism



Jan. 9, 1951 Filed Feb. 21, 1946 Aunnnuu H. M. STUELAND CLUTCH AND BRAKE MECHANISM 5 Sheets-Sheet l A TTORNE Ys.

Jan. 9, 1951 STUELAND 2,537,557.

CLUTCH AND BRAKE MECHANISM Filed Feb. 21, 1946 5 Sheets-Sheet 3 FIG. 6

ATTORNEYS.

Patented Jan. 9, 1951 CLUTCH AND BRAKE MECHANISM Harold M. Stueland, East Moline, 11L, assignor t Deere & Company, Moline, 111., a corporation of Illinois Application February 21, 1946, Serial No. 649,332 1 8 Claims. 1

The present invention relates generally to power transmitting mechanism, and more particularly to clutch and brake mechanism, and is specifically related to clutch and brake mechanism of the type used for mechanical hoisting apparatus, and has for its principal object the provision of a novel and improved clutch and brake assembly, in which the clutch and brake elements are disposed within opposite ends of a rotatable drum, each of the clutch and brake elements comprising an expansible shoe disposed within an internal cylindrical frictional surface within the drum near the end of the latter.

A further object relates to the provision of a novel and improved means for centering the clutch and brake shoes within the ends of the drum, when the shoe is in relaxed or contracted position.

Still another object relates to the provision of a single master control shaft connected with the clutch and brake actuating mechanism for actuating the clutch mechanism when the master control shaft is rocked in one direction from a neutral position, and for actuating the brake mechanism when the master control shaft is rocked in the opposite direction from the neutral position.

Still another object relates to the provision of a spring connected with the master control shaft, whereby the latter is urged toward a positio'n in which the brake mechanism is applied, but can be rocked by means of a foot actuated pedal from the braking position, through the neutral position to the clutch actuating position.

Still another object relates tothe provision of a novel and improved booster mechanism for actuating the clutch mechanism. More specifically, an object of my invention has to do with the provision of control connections between the booster clutch drum and the shoe expanding mechanism, which insures that the engagement pressure between the clutch shoe and its drum is substantially constant, regardless of the amount of pressure applied by the operator against the pedal.

A still further object relates to the provision of means for adjusting the pressure of the clutch shoe against the drum, and to compensate for wear between the frictional surfaces.

These and other objects and advantages of my invention will be apparent to those skilled in the art after a consideration of the following description, in which reference is had to the drawings appended hereto, in which Figure 1 is a side elevational view of a clutch and brake assembly embodying the principles of my invention;

Figure 2 is an elevational view taken in section along a line 22 in Figure 1;

Figure 3 is a sectional elevational view taken along a line 33 in Figure 2, showing the details of the clutch drum and shoe;

Figure 4 is a fragmentary sectional elevational view taken along a line Ai-4 in Figure 3 and showing one of the ends of the clutch shoe;

Figure 5 is an enlarged sectional view taken along a line 5-5 in Figure 1, showing the details of the resilient connection through which power is transmitted to actuate the clutch mechanism; and

Figure 6 is a fragmentary elevational view,

drawn to a smaller scale, showing the clutch and brake assembly mounted on the rear axle housing of a tractor, for use with a tractor mounted loader.

Referring now to the drawings, the clutch and brake assembly is indicated in its entirety by reference numeral l9 and comprises a central,

relatively stationary supporting shaft i, secured rigidly to a pair of side frame members l2, l3, one end of the shaft ll being welded to one of the members !2, while the other end of the shaft l! extends through a hub or sleeve it, which is rigidly welded to the opposite frame member !3. The shaft H is secured rigidly to the hub 14 by means of a pin i5, which is inserted through aligned apertures inthe hub l4 and shaft H, respectively.

The power transmitting mechanism includes a driving member 2!! and a driven member 2 1, both of which are rotatably mounted on the stationary shaft H, by means providing for independent rotation about the axis of the shaft H. The driving member 2% comprises a disk-like wheel having a hub 22 journaled on the shaft H and a peripherally extending V-shaped groove 23 adapted to receive a conventional V belt 24, through which power is transmitted to the driving member 20.

The driven member 2| comprises a drum, the two ends 25, 26 of which are open, mounted on a centrally disposed radially extending web 21 car'- ried on a hub 23, which is journaled on the stationary shaft H. The web 21 is provided with a plurality of openings 29 to provide for ventilation of the mechanism and also to decrease the weight of the driven member 2i The drum 2! is pro vided with a pair of interior cylindrical frictional surfaces 3d, 31 disposed adjacent the two open $11 .1 2 re pectively, and on opposite sides of the central supporting web 2?. The surfaces 30, 3| are defined by a pair of annular inserts 32, 33, respectively. These inserts can be replaced when they are worn out.

A pair of annular expansible shoes 34, 35 are disposed within the cylindrical frictional surfaces 30, 3|, respectively, and are adapted to be expanded into frictional gripping relation with the internal surfaces 30, 3| of the drum 2|. Each of the shoes 34, 35 is provided with a pair of cir cumferentially spaced end abutments 45, between which is inserted a flattened cam having rounded edges. The cam shaft for the shoe 34 is numbered 42 and that for the shoe 35 is numbored 43 (Fig. 2). The two cam shafts 42, as extend axially out of the end of the drum 2| and are journaled for rocking movement in a pair of journal bearings 44, 45, respectively. As best indicated in Figure 3, rocking the cam shaft id in either direction causes the fiat cam 46 to spread apart the spaced abutments 40, thereby expanding the shoe 35 into frictional engagement with the interior surface 3|. Each of the shoes 34, 35 is provided with a helical tension spring 45, connected with a pair of hooks or lugs 57 formed integrally with the shoe 35 on opposite sides of the pair of abutments 45. The spring 48 tends to pull the abutments 40 together to contract the shoe 35 as soon as pressure is relieved from the cam shaft 43. Each of the cam shafts d2, 43 is provided with a cylindrical neck 55 of reduced diameter, which is gripped between the abutting ends 40 of each of the shoes. Each of the abutments 40 is recessed, as indicated at 5|, to fit the neck portion 50 of the cam shaft associated therewith, and thus to center the shoe within the associated cylindrical frictional surfaces 30, 3|.

One of the bearings 45, in which the cam shaft 43 is journaled, is mounted On the driving member 20, preferably cast integrally therewith. The cam shaft 43 extends through the bearing 45 and carries on its outer end an actuating arm 52, pref erably welded thereto. A snap ring 53 engages a peripheral groove 54 in the cam shaft 43 on the inner side of the driving wheel 28, to prevent the cam shaft 43 from moving axially through the bearing 45 out of the end of'the drum 2i. Thus, it is now evident that the cam shaft 43 is rotated during operation in an orbit about the shaft H and drives the shoe 35 through the cam 5| and abutments 40, which are secured in engagement with the cam 4| by the spring 45, Thus, normally theshoe rotates within and with respect to the frictional surface 3| Without exerting any pressure thereon. However, by rocking the cam shaft 43, the cam 4| can be turned to force apart the two abutments 59, causing the shoe to expand within the frictional surface 35 and causing the driven member to rotate with the driving wheel 20 about the shaft The cam shaft 43 is rocked within its bearing 45 during the rotation of the driving wheel 26, by means of a booster clutch drum 58, provided with a cylindrical rim surface 65 carried on a radial web 52 mounted on a hub 63, which is journaled on an axially extending sleeve 54, which is preferably formed integrally with the hub 22 of the'driving member 28 and journaled on the ccn- .tral shaft H. The booster drum 65 is connected with the cam shaft actuating arm 52 by means of a resilient connecting device indicated in its en- ,tirety by reference numeral 65, which will be described later' in greater detail. Hence, although the drum is mounted for rotation with respect to the driving member 20 (on the hub or sleeve 5 of the latter), the drum is in fact driven by and rotates normally with the driving member, inasmuch as the resilient device 56 is connected at one end to the drum B0 and at its other end to the arm 52, which is carried by the rockshaft 43 which is in turn carried by the driving member 20. However, the angled relationship of the arm 52 and device 56 is such that any variation in the relative rotative speeds of the member 25 and drum E55, will effect relative angular or rocking movement between the two, particularly since the resilient device 66 is connected to the booster drum at a point spaced radially outwardly from its axis of rotation, with the result that such angular rocking movement of the booster drum 50 relative to the driving wheel 25 will cause a force to be transmitted through the connection 55 to the actuating arm 52 to rock the cam shaft 13.

This relative rocking or angular shifting movement between the booster drum and drive wheel 20 is accomplished during rotation of the drive wheel 2|! b stopping or retarding the drum 60 by means of a brake band 61 having a lining 68 wrapped around the surface 5| of the booster drum 53. The brake band 61 is provided with a tubular connector 69 at one end thereof, which engages a pin 70, secured to the frame member I2 and extending inwardly therefrom. The opposite end of the band 5? is attached to a sleeve H, disposed tangentially relative thereto, and through which sleeve extends a threaded rod 12. A helical compression spring 13 encircles the lower end of the rod '12, which is provided with a pair of lock nuts 4 at the outer end of the spring 13. Another pair of lock nuts 15 are provided on the rod 12 above the sleeve II. An upward movement of the rod 12 acts through the compression spring 13 to shift the sleeve 1| upwardly, and thus to wrap the brake band 61 tightly around the drum surface 6!, thereby braking the drum 60 and causing it to shift angularly relative to the driving wheel 29. Hence, it is evident that with the driving wheel 20 rotating in a clockwise direction as indicated by the arrow in Figure 1, an application of the brake band 67 on the drum 60 will retard the clockwise rotation of the latter sufiiciently to cause a relative angular displacement of the drum 6B in a counter-clockwise direction, thereby exerting an upward force through the resilient connection 86 to shift the actuating arm 52 upwardly, as viewed in Figure 1. This causes the rockshaft 43 and cam 4| to rock in a counterclockwise direction, thereby spreading the abutment-s 40 and engaging the clutch shoe 35 with the clutch drum 2|, which thereupon rotates in a clockwise direction along with the driving member 20. As soon as the upward force against the rod 12 is released, the frictional braking surface of the brake band 61 against the drum 6! is released, permitting the spring 46 to gather the abutments 45 together to contract the clutch shoe 35 and disconnect the latter from the driven member 2|. The action of the spring 46 is aided by means of a tension spring 15 connected to a lug H on the connecting member 66 and anchored to a lug T8 fixed to the side of the driving wheel 26. The tensional force of the spring 16 tends to pull the arm 52 downwardly, as viewed in Figure 1, and tends to shift the booster drum 5!) angularly in a clockwise direction relative to the driving member 28.

Heretofore, booster drums have been connected with their associated clutch element by means of non-resilient linkage, with the result that a strong ass-2, 55.7

5 application of force to a rod comparable "to the rod 12 :causes the brake band to grab on the braking surface of the booster drum, and thus causing excessive forces to :be transmitted to the also the means whereby the force transmitted;

from the booster clutch drum to the came-shaft!!! is also limited to apredetermined amount. The

operating rod I2 has an upper end portion 80 which is turned at right angles through a .slot 8] in an operating arm 82, which extends radially from a manually actuated control shaft83. The arm 82 is formed with a hub :84 secured rigidly to the shaft 83 by a pin 85. The hub 84 is-provided with an oppositely extending stop :arm '86,

which curves laterally across the edge of the .frame member I 2 and isprovided with a threaded aperture 81, within which is mountedaset screw 88. The end-of :the set screw '88 engages the edge of the frame member -I2 when the rocksha'ft '83 is rocked in a clockwise direction to pull the rod I2 upwardly, and the set screw 88 can beiad'justed to permit any desired extent of rocking movement of the rockshaft 83. This adjustment can 'be made in such a manner that a predetermined amount of stress is applied to the compression 1 spring IS, with the end of the 'set screw '88 in engagement with the edge of the frame member I 2,

so that regardless of the amount of pressure applied by the operator to rock the rockshait 83,

a predetermined amount of pressure is exerted by the compression spring 'I3aga'inst the brake band 61, A look nut 89 secures the set screw '88 inadjusted position. Adjustment of the set screw 88 can be made from time to time to compensate for wear in the lining $3 of the "brake band 61. The rockshait 83 is journaled in a pair of sleeve bearings 90, 9| which are supported within :suitable apertures in the upper ends of the .frame members I2, I3, respectively. A manually controlled operating lever 92, preferably :a foot pedal, is mounted on a hub 93 which is rigidly fixed by a key 94 to the extended end of the rockshaft 283.

As best shown in Figure 5, the resilient connecting device 6E5 comprises a clevis it having a pair of arms Isl pivotally connected to the end of the cam shaft actuating arm 52 by means ofa pin I022. The arms IBI are connected to the end of a tubular shank I83 having an axially extending cylindrical spring chamber we, the inner'en'd of which terminates at an aperture 535 of reduced diameter. A threaded rod let extends axially through the chamber 594 and the aperture I 85 and is provided with a nut Iii? threaded on the end thereof, on the opposite side of the aperture I95 from the chamber m4. A sleeve I98 is carried on the threaded rod Iilii and within the aperture I95. A nut engages threaded rod I 85 at the opposite end of the sleeve I88 and isprovided with a cylindrical "skirt pcrtion ill) which is slidable within the cylindrical chamber I04. The two nuts till, I 99 are tightened together against opposite ends of the sleeve I08 so that the rod I06, the sleeve its, and the nuts I87, I59 form a unitary structure which slides axially through the aperture I95. A helical compression spring III bears against the "inner-end of the skirt II I) andreacts against the inner end of the cylindrical chamber I114 adjacent the aperture I05. The outer end portion 11-2 of the rod I05 is turned at right angles and is inserted through a hole H3 in the web '62 at the booster clutch drum 60.

It is now evident that the amount of initial stress in the compression spring rII-I is determined by the length of the sleeve 108, but the length of the resilient connection 66 between the end II2 of the rod I06 and the pivotpin :I'DZ can be adjusted by adjusting both nuts IB'I, I 08 axially along the threaded rod I06.

The extent of angular movement of "the booster drum relative to the drive wheel 26 is limited by a pair of stop lugs I I5, I I6, Iform'ed integrally with the booster drumtfl and the driving member 20, respectively. Normally, the

stop lugs I I5, II6 are'separated, as indicated in Figure '1, but when the brake band 6'! is tightened on the drum 60, the latter is retarded while the member 29 moves withrespect thereto angularly about the axis of rotation until the stop lugs H5, H6 are moved into interengag'ing rel'ation with each other. During this amount of relative angular movement, the threaded rod I86 is forced inwardly "of the cylindrical recess Ills to apply pressure to the compression spring IiI to force the actuating arm 52 upwardly, as viewed in Figure 1. The amount of angular displacement of the booster drum v60 can be adjusted by adjusting the two nuts Illl, I 09 and the sleeve I08 therebetween along the threaded rod IE6. Hence, in any position of adjustment of the threaded rod IE6 relative to the clevi's I05, the amount of pressure exerted by the spring II I against the arm 52 is substantially constant. This amount of pressure through the arm 52 to the cam H and thus to the clutch shoe 35 gradually decreases as the shoe 35 and insert 31 wear,

but can be restored to the predetermined value by adjusting the nuts I61, I09 relative to the rod I 96. This adjustment can be made from time to time until either the shoe 35 or the insert :33 is worn out and requires replacing.

It is now evident that regardless of the amount of pressure that the operator exerts against the foot .pedal 92, the pressure of the shoe 35 expanding within the cylindrical friction surface "SI is substantially constant.

The hub 28 of the driven member 21 has a sleeve extension II'I, preferably formed integrally therewith, which extends axially along the shaft I1 and is journaled thereon. A sprocket H8 having a hub H9 is secured to the end of the sleeve I H by means of a suitable key I26. The sprocket H8 provides the means by which power is taken from the driven member 2I. posed at the open end 25 of the driven member .2! and is carried on a hub I22, which is ,iour-- naled on the sleeve III between the sprocket I I8 and the hub 28. Thus, foreign objects are prevented from entering the ends 25, 26 of the :driven member 2| by the closure plate 152i and the driving wheel 28. However, cooling air is permitted to flow through apertures 5 23 in the driving member 29, through the apertures 29 in the web 2"! of the driven member 2 I, and through the crack between the closure plate I2! and the end 25 of the member 2 I. I

The bearing 4A which supports the cam shaft 42 is formed integrally with the closure plate ill. The outer end of the :cam shaft 42 carrieslan A stationary closure plate or disk iZI is dis face 3|. is pivotally connected by means of a pin I26 (Figure 1) to a clevis I27 which is threaded on a actuating arm I25, preferably welded thereto,

and the cam shaft 42 is secured against axial movement relative to its bearing 44 by means of the snap ring 53 and groove 54. An upwardly extending arm I24 is formed integrally with the closure plate |2| and is provided at its upper end threaded rod I28 and secured in axially adjusted position by a lock nut I29. The upper end of the threaded rod I28 is provided with an end portion I30 bent at right angles therto and inserted into a slot [3| in an arm |32 which is formed integrally with a hub I33 rigidly fixed to the rockshaft 83 by a pin I34. The'hub I33 is also provided with an oppositely extending arm I35,

to which is connected a strong spring E35, the

spring being anchored at its other end to a pin I31 (see Figure 6).

It is now clear that the rockshaft 83 is a master control shaft, through which both the clutch and brake mechanisms can be controlled by the single foot pedal 92. The drawings show the parts in their normal positions in which the spring H36, acting through the arm I35 pulls upwardly on the threaded rod I28, the clevis if, and the actuating arm I25, to rock the brake control cam shaft 42, thereby spreading or expanding the brake shoe 34 against the braking surface 30 to hold the driven member 2| stationary, while the driving member 20 is driven idly by the belt 24 at a substantially constant speed. When the operator moves the foot pedal 92 in a clockwise direction, as viewed in Figure l, against the tension of the spring i36, the upward force against the brake arm 125 is first relieved, allowing the spring 46 within the brake shoe 34 to contract the latter, thereby freeing the driven drum 2| for rotation in either direction. Further pressure on the foot pedal 92 causes the bottom of the slot 8| in the arm 82 to engage the upper end 80 of the clutch actuating rod 12 to tighten the brake band 6'? on the booster drum 60. For the reasons explained herein before, the operator can step down on the foot pedal 92 with any amount of pressure, and the clutch shoe 35 will be expanded within the clutching surface 3|, causing the power to be transmitted from the drive belt 24 to the sprocket i I8.

When the operator lifts his foot from the pedal $2, causing the latter together with the master control shaft 83 to be rocked in a counterclockwise direction by the tension of the spring I 36, the clutch shoe 35 is first released, and further movement of the foot pedal 92 causes the brake shoe 34 tabs expanded to stop the rotary movement of the driven member 2|. The lost motion between the bent ends 80, 130 of the threaded rods i2, i213 in the slots 8|, I-3I insures that the clutch and brake mechanisms are applied independently within different portions of the range of rocking movement of the master control shaft 83.

The brake mechanism can be adjusted for Wear 'I42 secured to the boss MI by bolts I43. )ucket supporting push arm I44 is pivotally con- 'by loosening the lock nut 129 and turning the threaded rod I28 into or out of the clev'is I21. By shortening the rod I28 and clevis I 21 the brake shoe can be taken up for wear until the shoe 34 or the insert 32 is worn out and replaced.

Figure 6 shows a typical installation of the clutch and brake mechanism I0 on a tractor axle housing I40 of the type provided with bosses |4| for securing the implement to the axle housing I40. The implement illustrated in Figure 6 is a loader of the type mounted across the front of a tractor and includes a vertically disposed mast A nected at I45 to the lower end of the mast I42 beneath the tractor axle I46 and extends forwardly therefrom, as described in detail in my co-pending application, Serial No. 652,504, filed March '7, 1946, now Patent No. 2,489,469. A winding drum I4! is rotatably disposed on a shaft I48 which is supported in suitable lugs I49 secured to the mast 42 near the bottom thereof. -A lifting cable I50 is wound on the drum I41 and extends forwardly along the arm M4 and is used for raising and lowering the bucket in a manner described in the co-pending application' The winding drum I4! is provided with a drive socket -|5I, which is connected to receive power from the sprocket M8 by means of a drive chain I52.

The assembly I0 is supported between a pair of laterally spaced supporting plates I53, which are rigidly secured to the mast I42, the plates I53 having aligned apertures I54, within which the bearing sleeves 90, 9| are journaled. The lower ends of the frame members I2, I3 are provided with transversely aligned apertures I55 which receive a pair of bolts I56 adapted to be inserted through arcuat slots I5! in a pair of plates I58, which are rigidly fixed to the mast I42. The slot I5! is curved about the axis of the master control shaft 83 as a center to pro- .vide for shifting the frame members l2, I3 about the last named axis to adjust the tightness of the belt 24, after which the bolts I56 can be tightened to secure the lower end of the frame members I2, I3.

The crank shaft of the tractor is indicated at I60, on which is mounted a flywheel IISI. The drive belt 24 is trained over a V-belt pulley I62, which is rigidly secured to the end of the crank shaft I 60.

During operation, the crank shaft I60 turns at a substantially constant rate of speed, driving the driving wheel 20. Normally the brake is held in engaged position by the spring I36, holding the bucket supporting arms 644 at any desired elevation. The operator can lower the bucket by pressing the pedal 92 forwardly to the neutral position, in which both the brake and clutch shoes 34, 35 are disengaged, allowing the weight of the bucket and arms I44 to unwind the cable I50 from the drum I43. B pressing the foot pedal 02 forwardly to the position in which the set screw 88 engages the frame member I2, the clutch is engaged, causing the driven member 2| to turn the sprocket H8 in a direction to wind the cable I50 on the winding drum I 41.

I do not intend my invention to be limited to the exact details shown and described herein, except as limited by the claims which follow.

I claim:

1. In a clutch assembly, a driving member and a driven member supported for rotation about a common axis, said driven member having an internal cylindrical surface coaxial with said memhere, afi expansible shoe disposed within said cylindrical surface, a rockable control shaft journaled on said driving member and having a camming element for expanding said shoe responsive to rocking movement of said shaft, a control dr'um mounted coaxially of said driving member and normally rotatable with the latter but shiftable angularly relative thereto, resilient means connecting said control shaft with said controldrum providing for rocking said shaft by angular movement of said drum relative to said driving member, braking means engageable with said drum for effecting said relative angular movement, and stop means arranged and constructed to limit the extent of said relative an gular movement.

2. In a clutch assembly, a driving member and a driven member supported for rotation about a common axis, said driven member having an internal cylindrical surface coaxial with said members, an expansible shoe disposed within said cylindrical surface and having a pair of peripherally spaced ends, a cam shaft rockably mounted on said driving member and extending between the ends of said shoe, a cam element on said cam shaft between said spaced ends of the shoe for expanding the latter into engagement with said surface responsive to rocking movement of said cam shaft, said shoe ends having recesses for receiving a cylindrical portion of said cam shaft therebetween to center said shoe in relaxed position, a control drum mounted coaxially of said driving member and normally rotatable with the latter but shiftable angularly relative thereto, resilient means connecting said control shaft with said control drum providing for rocking said shaft ,by angular movement of said drum relative to said driving member; braking means engageable with said drum for effecting said relative'angular movement, and stop means-arranged and constructed to limit the extentof said'relative angular movement. v

A clutch and brake assembly comprising'a support; a pair ofdriving and driven members journaled on said support, clutch mechanism for connecting said driving and driven members including interengageable frictional surfaces on said members and control means for engaging said surfaces including a clutch actuating element and a booster drum coupled thereto, said booster drum being rotatably mounted adjacent said driving member and shiftable angularly relative thereto about the axis of rotation to engage said clutch surfaces, a master control shaft spaced from said driving member and mounted rockably on said support, braking means engageable with said booster drum and connected with said master shaft to shift said booster drum relative to said driving member responsive to rocking movement of said master shaft in one direction from a neutral position, and braking means for said driven member comprising a pair of interengageable frictional braking surfaces and an actuating element for engaging the latter, and means connecting said actuating element to said master control shaft for engaging said surfaces responsive to a rocking movement of said master shaft in the opposite direction from said neutral positionf 4. A clutch and brake assembly comprising a support, a pair of driving and driven members journaled on said support, clutch mechanism for connecting said driving and driven members including interengageable frictional surfaces on d membe a dlco r mea managin Said fa in ud a, cl tcha tu ine ele m n an al qosie d umcoupledtneretql. said os r dru ein tab m unt d, a jacent said driving ,jm mber nd shiftable. an ularly relative ,thereto about the axis of rotation, to engage said clutch surfaces, a master control Sh fi q s fr m said.d Yinsmemb n.and dr ka y n Sa d s pp rt bra in means engageable with saidlbo oster drum andconnected with said master shaftto shiftsaidboosterdrum a i e t said. d n mem n espon ivewto rocking movement of, said I master shaft ,irrone direction from a neutral A position, and, braking m s er id drir nlmsmb em ris aa ai of i b e, ii nallbrak n ur ace and an actuating, element for engagingthe lat; ter, means connecting said actuating eleme t to said master controlshaftfor engaging said. 5 r1, faces responsive to a roekingmovementpf said master? Shaft in b po' iis dire. i n fr m, aid neutral posit a s ie Isen scied was m s: ter control shaft to urge the latter toward a p9,;- Sifibfi in which i ak surfa e are en a ed, and a feot'ope'rated leverattached to saidmaster shaft and shiftable again's t the pressure gf disposed within said u u j v 7 x m shoe, navin a' pair of periphe'ally spaced ab mentsya pair at central shafts extending in g drum ends, respectively, angina/ing cam port'ons eng'ag'eable'withthe associated abutments fofr ex;

spectivelml a pair of expansible annular shoes.

panding" sai'dfsh'oesfby rocking move ent of said,

shafts, respectively, afpair br jppeitsro s d shafts disposed adj cent t e endsof s d ruin, respectively, chara teri'zd in ,that, one of said controlsl'faft supports comprise erasable driving member and said control means includes a booster drum disposed coaxial with said driving member adjacent the latter and shiftable angularly relative thereto about the axis of rotation, means connecting said booster drum with the associated control shaft providing for actuation of the latter by angular shifting movement of said drum, and braking means engageable with said booster drum.

6. In mechanism of the class described, a driven member comprising a drum having a central support-ing web, and a pair of open ends, a pair of internal cylindrical frictional surfaces within said drum adjacent said open ends, respectively, a pair of expansible annular shoes disposed within said drum ends, respectively, each shoe having a pair of peripherally spaced abutments, a pair of control shafts extending into said drum ends, respectively, and having cam portions engageable with the associated abutments for expandin said shoes by rocking movement of said shafts, respectively, a pair 'of supports for said shafts disposed adjacent the ends of said drum,

respectively, characterized in that one of said" associated control shaft providing for actuation of the latter by angular shiftin movement of said drum, and braking means engageable with said booster drum, the other of said control shaft supports being relatively stationary, said control means including a brake control lever connected to the control shaft mounted on the last named support.

-'7. In mechanism of the class described, a driven member comprising a drum having a central supporting web, and apair of open ends, a pair of internal cylindrical frictional surfaces within said drum adjacent said open ends, respectively, a pair of expansible annular shoes disposed within said drum ends, respectively, each shoe having a pair of peripherally spaced abutments, a pair of control shafts extending into said drum ends, respectively, and having cam portions engageable with the associated abutments for expanding said shoes by rocking movement of said-shafts, respectively, a pair of supports for said shafts disposed adjacent the ends of said drum, respectively, characterized in that one of said control shaft supports comprises a rotatable driving member and said control means include a booster drum disposed coaxial with said driving member adjacent the latter and shiftable angularly relative thereto about the axis of rotation, means connectin said booster drum with the associated control shaft providing for actuation 'of the latter by angular shifting movement of said drum, braking means engageable with said booster drum, a rockably mounted master control shaft spaced from said booster drum, a connection between said master control shaft and said braking means for braking said booster drum when said master control shaft is rocked in one direction from a neutral position, the other of said control shaft supports being relatively stationary, and a connection between said master control shaft and the control shaft mounted on the last named support for actuating the latter control shaft to brake said driven member when 8. In combination, a drum having an annular internal friction surface; an expansible shoe, having an external friction surface engageable with the drum surface. carried within the drum and constructed as a substantially circular ringlike member interrupted in its circular extent at but one portion thereof to provide a pair of peripherally spaced apart ends respectively having opposed, spaced apart flat faces generally transverse to the shoe periphery; an operating member between the shoe end faces; means mounting said operatin member for movement with respect to the shoe and drum between an inactive position and an active position; means normally maintainin the operating member in inactive position; means on the operating member providing a pair of opposite, flat cam faces respectively in face-to-face relationship with the shoe end faces when the operating member is in in-- active position and operable to spread the shoe ends when said operating member is moved to active position; spring means connected across the shoe ends to normally hold the shoe end faces in face-to-face engagement with the operating member faces to effect a clamping action of the shoe on the operating member whereby said operating member serves, in its inactive position, as the sole means for supporting and centering the shoe in the drum.

HAROLD M. STUELAND.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 794,291 Ford-Smith et al. July 11, 1905 821,680 Turner May 29, 1906 965,825 Locke et a1. July 26, 1910 1,764,923 Wilson June 17, 1930 1,813,068 Mitchell et al. July '7, 1931 1,834,222 Ronk Dec. 1, 1931 2,402,400 Hewitt et a1. June 18, 1946 2,443,042 Kriegbaum June 8, 1948 

